The invention relates to a contact anti-microbial covalently bound to a polymeric material that may be suitable in a variety of applications such as film and container packaging of foodstuffs, cosmetics, medical equipment and devices, environmental, hygienic and sanitary applications, as well as other consumer and commercial use. In one aspect of the invention and not as a limitation, the invention provides anti-microbial compositions covalently linked to packaging and processing films for foodstuff and methods for inhibiting or preventing growth of microbes such as bacteria, molds and yeast on food surfaces.
In this aspect of the invention, an anti-microbial agent is covalently bound to polymeric films used to package and wrap food for the purpose of reducing surface bacterial, fungus, and/or virus count and/or increasing the shelf life of the enveloped food article.
Prior art of interest includes U.S. Pat. No. 4,532,128 (herein incorporated by reference), which relates to polymeric quaternary ammonium compounds having recurring vinylbenzyl ammonium units. The quaternary ammonium units preferably have 2 alkyl substituents of 1 to 4 carbons and 1 alkyl substituent of 4 to 12 carbons. U.S. Pat. No. 4,532,128 specifically relates to non-film materials that have antimicrobial properties and are particularly useful for preserving ophthalmic solutions.
The present invention preferably relates to film compositions capable of killing microbes and therefore useful for food preservation. “Food preservation”, as that term is used herein, includes methods, which guard against food poisoning as well as methods, which delay or prevent food spoilage due to microbes. Food preservation keeps food safe for consumption and inhibits or prevents nutrient deterioration or organoleptic changes causing food to become less palatable.
“Food spoilage”, as that term is used herein, includes any alteration in the condition of food which makes it less palatable including changes in taste, smell, texture, or appearance. Spoiled food may or may not be toxic.
“Food poisoning”, as that term is used herein, refers to mammalian diseases caused by ingestion of food contaminated by pathogenic viruses, molds, or bacteria and/or their toxins. Pathogen-contaminated food does not necessarily show any organoleptic sign of spoilage. Bacterial food poisoning may be caused by either infection of the host by the bacterial organism or by action of the toxin produced by the bacteria either in the food or the host. (See U.S. Pat. No. 5,573,801, incorporated herein by reference). Initial attempts to prevent food spoilage and food poisoning were trial and error. The use of drying, salting, and smoking of food found favor in early ages. Technological advances later showed that chemical agents such as nitrites/nitrates, sulfites, acetic acid (pickling), and antibiotics (natamycin/nisin) could be beneficially applied to foodstuffs. Polymeric films for food packaging have seen increasing use as the importance of retail supermarkets and home use of refrigerators and microwaves has risen. Polymeric films are used because of their convenience in applications of storage and cooking. The advantageous properties are dinginess, air permeability, anti-fogging, and transparency. There are examples of polymeric films which incorporate metallic (See U.S. Pat. Nos. 5,929,133; 6,126,931 and 5,827,524, incorporated herein by reference) and organic (See U.S. Pat. Nos. 5,906,825; 5,759,844; 5,639,466; 5,573,801; 5,573,800; and 5,573,797, incorporated herein by reference) anti-microbials in a non-covalent fashion for use with foodstuffs. There are several disadvantages to these prior art approaches. For example, because the anti-microbial is not covalently bound, it may be leached from the polymeric film, thus the anti-microbial effect decreases with time. Another disadvantage is that some types of anti-microbials are toxic to mammalian species as well as bacteria and would be inappropriate for food applications where the agent could migrate from the package to the foodstuff. Yet a further disadvantage is that an anti-microbial which leaches from the polymeric film may alter the taste and/or appearance of the foodstuff contained within. In the case of films used in cooking, the process of heating may accelerate the migration of the anti-microbial from the film to the foodstuff such that higher levels than acceptable are found on the foodstuff. Thus, the prior art is deficient in affording a contact anti-microbial covalently bound to a polymer which inhibits the growth of microbes while reducing the possibility of leaching or migration of the anti-microbial from the polymer in a form that may be suitable for a variety of applications such as film and container packaging of foodstuffs, cosmetics, medical equipment and devices, environmental, hygienic and sanitary applications, as well as other consumer and commercial use.